Washing machine

ABSTRACT

A washing machine for minimizing damage to laundry and enabling effective washing of the laundry. The washing machine includes a water tub, a drum, and a control unit. The drum is installed in the water tub so as to rotate in a forward and/or a reverse direction. The control unit controls the rotation directions and angles of the rotation of the drum to cause an asymmetric swing motion of the drum.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 2004-71895 filed on Sep. 8, 2004 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a washing machine, and more particularly to a drum type washing machine having a drum adapted to rotate about a horizontal rotation axis.

2. Description of Related Art

A conventional drum type washing machine generally includes a water tub installed in a machine body and adapted to contain wash or rinsing water, and a drum installed in the water tub, the drum being rotated by a driving force from a motor and being adapted to carry out laundry wash and spin-dry cycles. Such a drum is perforated with a plurality of small holes, allowing the wash or rinsing water to flow between the drum and the water tub and, in the spin-dry cycle, to centrifugally drain water from laundry, the water to be discharged into a space between the drum and the water tub through the small holes.

In the above-described drum type washing machine, when the drum rotates, the laundry in the drum is raised along an inner peripheral wall surface of the drum, and then dropped due to gravity from the vicinity of an apex, so that the laundry is washed by way of shock and friction generated during the dropping.

However, the above-described general washing manner using the drum type washing machine has a problem in that the laundry, specifically, silk or wool laundry, is vulnerable to damage by shock or friction. In order to eliminate this problem, Japanese Patent Laid-Open Publication Nos. H09-276582 and H09-248395 disclose control methods of drum type washing machines, which will now be explained.

Japanese Patent Laid-Open No. H09-276582 discusses minimizing damage to the laundry by repeatedly swinging the drum during the rotation thereof within an extent not causing movement of the laundry. In this case, however, since a two-revolution operation of the drum is added in the course of laundry douse and wash cycles for overturning the laundry, resulting in a limited reduction in damage to the laundry.

In Japanese Patent Laid-Open No. H09-248395, the wash cycle of the laundry is divided into first half and second half periods. During the first half period, the wash water in the water tub is kept at a first level and the drum rotates by a first rotation angle, causing the laundry to be dropped and overturned. In succession, during the remaining second half period, the wash water in the water tub is kept at a second level higher than the first level and the drum rotates by a second rotation angle smaller than the first rotation angle, allowing the laundry to be swung in a completely immersed state in the wash water so as to reduce damage to the laundry. In this case, however, in order to sufficiently douse the laundry with the wash water kept at a low level in the laundry douse cycle, the laundry must be dropped from a high swing angle of the drum. This may cause damage to the laundry.

Furthermore, although the swing angle of the drum must be kept at 120° in the wash cycle, such a swing angle is insufficient to overturn the laundry and hence prevents complete dousing of the laundry with the wash water and even washing of the laundry. Therefore, this increases the usage of the wash water, deteriorating a water saving advantage of the drum type washing machine.

BRIEF SUMMARY OF THE INVENTION

The present invention has been made in view of the problems involved with the above-described conventional drum type washing machines, and an aspect of the invention is to provide a drum type washing machine which can minimize damage to laundry during washing and enables effective washing of the laundry.

In accordance with an aspect of the present invention, there is provided a washing machine including: a water tub; a drum in the water tub, the drum being rotatable in a forward rotation direction at a forward rotation angle and a reverse rotation direction opposite of the forward direction at a reverse rotation angle; and a control unit adapted to control the rotation directions and angles to yield asymmetric swing motion of the drum.

In accordance with another aspect of the present invention, there is provided a washing machine including: a water tub; a drum in the water tub, the drum being rotatable in a forward direction and a reverse rotation direction opposite of the forward direction; and a control unit adapted to control the rotation of the drum to yield an asymmetric swing motion of the drum. During the asymmetric swing motion, the control unit controls forward and reverse rotation angles so that a reference position of the drum is displaced in the forward rotation direction.

In accordance with another aspect of the present invention, there is provided a washing machine control method, including: determining whether a set wash mode is an asymmetrical swing mode in which a drum is alternately rotated in a forward direction and a reverse direction by respective forward and reverse rotation angles; asymmetrically swinging the drum, when the set wash mode is the asymmetrical swing mode, so that the drum alternately rotates in the forward direction and the reverse direction by the respective forward and reverse rotation angles, the alternately rotating causing one of a net forward rotation of the drum and a net reverse rotation of the drum.

Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following detailed description, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a perspective view illustrating a drum type washing machine according to an embodiment of the present invention;

FIG. 2 is a block diagram illustrating a control system of the washing machine shown in FIG. 1;

FIG. 3 is a diagrammatic view illustrating a drum and water tub of the washing machine shown in FIG. 1;

FIGS. 4A and 4B are diagrammatic views illustrating the asymmetric swing motion of the washing machine according to the embodiment of the present invention;

FIG. 5 is a diagrammatic view illustrating gradual forward rotation of the drum caused by the asymmetric swing motion of the washing machine according to the embodiment of the present invention;

FIG. 6 is a graph explaining the concept of the gradual forward rotation of the drum shown in FIG. 5; and

FIG. 7 is a flow chart illustrating a control method of the washing machine according to the embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT

Reference will now be made in detail to an embodiment of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiment is described below to explain the present invention by referring to the figures.

FIG. 1 is a perspective view illustrating a drum type washing machine according to an embodiment of the present invention. As shown in FIG. 1, the drum type washing machine of the present embodiment includes a water tub 102 installed in a machine body 100 and adapted to contain wash or rinsing water. Installed in the water tub 102 is a drum 108, which rotates upon receiving a driving force from a motor 110 and is adapted to carry out laundry wash and spin-dry cycles. Such a drum 108 is perforated with a plurality of small holes at a peripheral wall thereof, allowing the wash or rinsing water to flow between the drum 108 and the water tub 102 and, in the spin-dry cycle, water centrifugally drained from laundry to be discharged into a space between the drum 108 and the water tub 102 through the small holes.

In the above-described drum type washing machine according to the present embodiment, when the drum 108 rotates, the laundry in the drum 108 is raised along an inner peripheral wall surface of the drum 108, and then dropped due to gravity from the vicinity of an apex (i.e., the highest point), so that the laundry is washed by way of shock and friction generated during the dropping.

FIG. 2 is a block diagram illustrating a control system of the washing machine shown in FIG. 1. Referring to FIGS. 1 and 2, the washing machine according to the present embodiment includes: a control unit 202, a water level sensor 204, and an input unit 206. The control unit 202 controls the general operation of the washing machine including douse, wash, rinsing, spin-dry and dehydration (drying) cycles. The water level sensor 204 detects the level of the wash water supplied in the water tub 102 and delivers the detected water level value to the control unit 202. The input unit 206 enables for a user to select a desired wash mode, and transmits the selected wash mode to the control unit 202.

The drum type washing machine according to the present embodiment also includes a drive unit 210 adapted to drive the motor 110, a drain pump 116, a dehydration heater 216, and a display device 218. In the wash or rinsing cycle, the motor 110 rotates the drum 108 in forward or reverse directions for specified periods, and in the spin-dry cycle, rotates the drum 108 at a high speed. The drain pump 116 forcibly discharges the wash water from the water tub 102, and the dehydration heater 216 heats air introduced into the water tub 102, causing dehydration (drying) of the laundry using the heated air. The display device 218 indicates the operation state of the washing machine to a user.

FIG. 3 is a diagrammatic view illustrating the drum 108 and the water tub 102 of the washing machine shown in FIG. 1. As shown in FIG. 3, the drum 108 is positioned inside the water tub 102. The water is supplied into the water tub 102, and flows into the drum 108 through the small holes perforated throughout the peripheral wall of the drum 108. Under control of the control unit 202, the drum 108 rotates in the forward or reverse directions.

In the above-described washing machine according to the present embodiment, if the user selects a swing mode suitable to minimize damage to the laundry, the drum 108 carries out an asymmetric swing motion, rather than a continuous rotating motion, during the laundry douse or wash cycle. FIGS. 4A and 4B are diagrammatic views illustrating such an asymmetric swing motion of the washing machine according to the present embodiment, FIG. 4A showing a reverse rotation of the drum 108, and FIG. 4B showing a forward rotation of the drum 108. As can be seen from FIGS. 4A and 4B, in the swing mode according to the present embodiment, a forward rotation angle is larger than a reverse rotation angle. For example, the drum 108 rotates in a reverse direction CW by an angle of 45° as shown in FIG. 4A, and then rotates in a forward direction CCW by an angle of 60°, resulting in the forward rotation of 15°. That is, due to the difference between the forward and reverse rotation angles as stated above, even if the drum 108 alternately rotates in the forward direction CCW and the reverse direction CW, the net effect is that drum 108 gradually rotates in the forward direction CCW by an increment of 15° according to the progress of the swing motion. Consequently, laundry 402 is rotated in the forward direction CCW by an increment of 15°.

FIG. 5 is a diagrammatic view illustrating the gradual forward rotation of the drum 108 caused by the asymmetric swing motion of the washing machine according to the present embodiment. As shown in FIG. 5, if the swing mode begins, first, the drum 108 rotates reverse by the specified angle to set an initial position (as indicated by an arrow 0 shown in FIG. 5). Then, starting from the initial position, the drum 108 alternately rotates in the forward direction (as indicated by arrows 1, 3 and 5) and in the reverse direction (as indicated by arrows 2 and 4), carrying out the asymmetric swing motion. In this case, as a result of the difference between the forward and reverse rotation angles, the drum 108 gradually rotates in the forward direction CCW by the increment of 15° as explained in conjunction with FIGS. 4A and 4B. That is, the drum 108 simultaneously carries out both the swing motion and the gradual forward rotation.

FIG. 6 is a graph explaining the concept of the gradual forward rotation of the drum 108 shown in FIG. 5. In the graph, an x-axis represents time, and an y-axis represents a velocity command. As shown in FIG. 6, after the drum 108 is initialized in position as it rotates reverse (as indicated by reference numeral 0), it alternately carries out forward rotations (as indicated by reference numerals 1, 3 and 5) and reverse rotations (as indicated by reference numerals 2 and 4). Although velocity commands (amplitudes) of the forward and reverse rotations are the same as each other, a forward rotation angle is larger than a reverse rotation angle since a forward rotation time is longer than a reverse rotation time. Therefore, it will be appreciated that, even though the drum 108 continuously swings in the swing mode, the average of such forward and reverse rotations, indicated by a dashed-line 602, is biased in the forward direction CCW. This means that the drum 108 rotates forward on the average across the entire swing mode.

FIG. 7 is a flowchart illustrating a control method of a washing machine according to the present embodiment. As shown in FIG. 7, first, the desired wash mode is set (operation 702). In this case, it is determined whether the set wash mode, selected by the user, is the swing mode suitable to protect the laundry from excessive shock or friction generated upon rotation of the drum, or not (operation 704). If not, the corresponding wash mode is carried out (operation 706).

If the swing mode is selected, in an initialized state wherein the drum rotates reverse by the specified angle, the drum is controlled in a rotational direction so that it alternately rotates forward and reverse by the specified forward and reverse rotation angles (operation 708). After the lapse of a specified time corresponding to the swing mode, the swing mode ends (operation 710).

The above-described embodiment of present invention provides a drum type washing machine which can minimize damage to laundry, specifically, silk or wool laundry vulnerable by shock or friction caused during washing, as a result of carrying out asymmetric swing motion of a drum thereof. Further, according to the above-described embodiment of the present invention, since the drum simultaneously swings and gradually rotates forward, laundry can be easily overturned even by rotation of the drum across a small angle, resulting in a reduction of douse or wash time and enabling effective washing of the laundry. The gradual forward rotation, furthermore, enables continuous overturn of the laundry.

Although an embodiment of the present invention has been shown and described, the present invention is not limited to the described embodiment. Instead, it would be appreciated by those skilled in the art that changes may be made to the embodiment without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents. 

1. A washing machine comprising: a water tub; a drum in the water tub, the drum being rotatable in a forward rotation direction at a forward rotation angle and a reverse rotation direction opposite of the forward direction at a reverse rotation angle; and a control unit adapted to control the rotation directions and angles to yield asymmetric swing motion of the drum.
 2. The machine according to claim 1, wherein the control unit controls the rotation angles so that the forward angle of the drum is greater than the reverse angle of the drum during the asymmetric swing motion.
 3. A washing machine comprising: a water tub; a drum in the water tub, the drum being rotatable in a forward direction and a reverse rotation direction opposite of the forward direction; and a control unit adapted to control the rotation of the drum to yield an asymmetric swing motion of the drum, wherein during the asymmetric swing motion, the control unit controls forward and reverse rotation angles so that a reference position of the drum is displaced in the forward rotation direction.
 4. The machine according to claim 3, wherein the control unit controls the rotation angles so that the forward rotation angle is greater than the reverse rotation angle to cause gradual displacement of the reference position.
 5. A washing machine control method, comprising: determining whether a set wash mode is an asymmetrical swing mode in which a drum is alternately rotated in a forward direction and a reverse direction by respective forward and reverse angles; asymmetrically swinging the drum, when the set wash mode is the asymmetrical swing mode, so that the drum alternately rotates in the forward direction and the reverse direction by the respective forward and reverse rotation angles, the alternately rotating causing one of a net forward rotation of the drum and a net reverse rotation of the drum.
 6. The washing machine control method of claim 5, wherein the forward rotation angle is 60° and the reverse rotation angle is 45°.
 7. The washing machine control method of claim 5, wherein a difference between the forward and the reverse rotation angles is 15°.
 8. The washing machine control method of claim 5, wherein the one of the rotation angles is greater than the other of the angles.
 9. The washing machine control method of claim 5, wherein the alternately rotating yields continuous overturn of laundry in the drum. 